KR20160042877A - Liquid crystal coupled light modulation - Google Patents

Abstract

The liquid crystal coupled light modulation includes a light guide for guiding light by total internal reflection (TIR), a diffraction grating, and a liquid crystal interposed between the diffraction grating and the light guide. The liquid crystal has a state having a first refractive index to prevent total internal reflection and another state having a second refractive index to facilitate total internal reflection at the surface of the light guide. Wherein the liquid crystal in the first refractive index state is for couple out of a portion of the guided light to the diffraction grating and the diffraction grating is for providing a diffractive redirection of the coupled- will be.

Description

[0001] LIQUID CRYSTAL COUPLED LIGHT MODULATION [0002]

Optical modulators, or more generally electro-optical modulators, are used in a variety of applications from optical communication to electronic displays. For example, a light modulator may be used to modulate light emitted by a backlight in modern electronic displays. The light modulator is capable of modulating the emitted light in separate, spatially separated areas of the electronic display represented by pixels. For example, light emitted by the backlight may be passed through the optical modulator and modulated to change the intensity of the light emitted by the pixel. Optical modulators used in optical communications may use any of a variety of means including but not limited to amplitude modulation, phase modulation, and polarization modulation to code information for transmission into a light beam in an optical transmission path (e.g., a fiber optic cable) .

As indicated above, for example, a light modulator may be used to alter or modulate one or more of the amplitude or intensity, phase, and polarization of the light beam. An optical modulator (i.e., a light amplitude modulator) that modulates light using amplitude modulation is sometimes referred to as a light valve. For example, amplitude modulation in a light valve can be performed through a change in transmission (e.g., a transmissive light valve) or a change in reflection (e.g., a reflective light valve). For example, the change in the transmission is due to a change in the absorption characteristics of the light valve. The liquid crystal light valve generally provides amplitude modulation through a change in the transmission characteristic, for example, by using a polarization shift of the light passing through the liquid crystal light valve. The reflected light valve may utilize a change in the direction of the light beam provided by a micromechanical mirror, for example to affect the amplitude modulation of the light beam. Also, for example, amplitude modulation can be performed using a phase change in the light beam, such as in an interference measurement light valve.

Various features of embodiments according to the principles described herein may be more readily understood with reference to the following detailed description, taken in conjunction with the accompanying drawings, in which like reference numerals are used to refer to like elements throughout.
1 is a cross-sectional view of a liquid crystal coupled light modulator according to an example consistent with the principle described herein.
Figure 2 is a cross-sectional view of a liquid crystal coupled optical modulator according to an example consistent with the principles described elsewhere herein.
3A is a partial cross-sectional view of a liquid crystal coupled optical modulator in a first state according to an example consistent with the principle described herein.
FIG. 3B is a partial cross-sectional view of the liquid crystal coupled optical modulator of FIG. 3A in a second state according to an example consistent with the principle described herein.
4 is a block diagram of an electronic display according to an example consistent with the principles described herein.
5 is a flow chart of a liquid crystal coupled light modulation method according to an example consistent with the principle described herein.
Specific examples have other features added to or in lieu of those shown in the reference figures. These and other features are described in detail below with reference to the above-referenced drawings.

An example according to the principles described herein provides optical modulation using a liquid crystal based coupling between a light guide and a diffraction grating. In particular, a selectively variable refractive index (e.g., birefringence) of the liquid crystal is used to change or modify whether the light-modulated guided light described herein is coupled outside the light guide. The change in the liquid crystal based coupling out of the guided light results in a diffractive redirection and changes the amount of coupled out guided light delivered to the diffraction grating for light emission .

Unlike polarization-based liquid crystal optical modulation, the optical modulation according to the principle described herein does not use a pair of orthogonal polarizers. As such, a more compact and efficient optical modulator implementation using generally fewer number of layers and components than the polarization-based liquid crystal modulator can be provided. For example, during the exemplary application of the optical modulation using the liquid crystal-based coupling modulation described herein, there is a modulated backlight for the electronic display. In another example, the light modulation described herein may be applied to a modulated optical area (e.g., a display) such as but not limited to a display such as a non-limiting three-dimensional (3D) For example, an array of modulated beams or beamlets).

According to various examples of the principles described herein, the diffraction grating is used to redirect the light from the light guide by diffractive redirection. Wherein the change in the refractive index of the liquid crystal interposed between the diffraction grating and the light guide alternately facilitates coupling out of light from the light guide and transferring the coupled light to the diffraction grating for diffractive redirection To prevent or prevent the coupling-out light. For example, the light guide may be a light guide of a backlight of an electronic display. According to various examples, the diffraction grating comprises or consists of features (grooves, ridges, holes, bumps, material modifications, etc.) disposed adjacent the light guide.

The liquid crystal interposed between the diffraction grating and the light guide contacts the surface of the light guide. If the liquid crystal has a refractive index that matches or exceeds the refractive index of the material of the light guide, the liquid crystal substantially relaxes the refractive index condition for total internal reflection (TIR) in the light guide at the surface. Thus, total reflection is prevented (i.e., at the light guide surface in contact with the liquid crystal) since the light guide no longer supports total reflection. Alternatively, when the liquid crystal exhibits a refractive index smaller than the refractive index of the light guide material, the light guide normally operates to guide the light by total reflection. Further, according to various examples, the liquid crystal may be switched between a first refractive index that is equal to or greater than a refractive index of the light guide material, i.e., a 'light guide refractive index', and a second refractive index lower than the refractive index of the light guide. For example, the conversion may be provided by changing the state of the liquid crystal (e.g., the orientation of the molecules in the liquid crystal). According to some examples, the state change may be provided by an applied electric field. In another example, the state change may be provided by other means including, but not limited to, changes in temperature.

Herein, the 'diffraction grating' is defined as a plurality of features arranged to provide diffraction of incident light with the above feature. Furthermore, by definition herein, this feature of the diffraction grating may be a feature formed on at least one of the surface, the surface, and the surface of a material layer or structure layer that provides or supports the diffraction grating. For example, the material layer may be a sheet of material (e.g., a dielectric) adjacent to but spaced from the surface of the light guide. The features may include any of a variety of features or structures that diffract light, including, but not limited to, grooves, ridges, holes and bumps on the material surface. For example, the diffraction grating may include a plurality of parallel grooves at the material surface. In another example, the diffraction grating may include a plurality of parallel raised portions formed outside the material surface. In some examples, the feature may include material variations (e.g., variations in material refractive index) within the material surface.

According to some examples, the diffraction grating is substantially transparent (i.e., does not substantially absorb at the operating wavelength of the diffraction grating) so that light is transmitted through the diffraction grating. By definition herein, this substantially transparent diffraction grating is referred to as a " transmissive " diffraction grating. In another example, the diffraction grating comprises a reflective material (e.g., a metal layer) and the light incident on the diffraction grating is diffracted as well as diffracted from the surface of the diffraction grating. By definition, the diffraction grating comprising the reflective material is a " reflective " diffraction grating.

In some examples, the plurality of features of the diffraction grating may be arranged in a periodic arrangement. In another example, the diffraction grating may include features arranged in an aperiodic arrangement. In some examples, the diffraction grating may include a plurality of features arranged in a one-dimensional array. For example, the plurality of parallel grooves is a one-dimensional array. In another example, the diffraction grating may include features of a two-dimensional (2D) arrangement. For example, the diffraction grating is a two-dimensional array of bumps on the material surface. The features (e.g., grooves, ridges, holes, bumps, etc.) may be any of a variety of cross-sectional shapes or profiles that provide diffraction, including, but not limited to, a rectangular profile, a triangular profile, Lt; / RTI >

에서 발생한다. 주기적, 투과성 회절격자에 의해 공급된 상기 회절 각도

은 수학식 1에 의해 주어질 수 있다. Here, 'diffractive redirection' is defined as the redirection of an electromagnetic wave (e.g., light) as a result of diffraction (e.g., by a diffraction grating). For example, the diffraction grating may be used to redirect light coupled out of the light guide by diffractive redirection. For example, the diffractive redirection may be substantially a diffraction angle

Lt; / RTI > The diffraction angle < RTI ID = 0.0 >

Can be given by Equation (1).

는 상기 광의 파장이고,

은 회절 차수이며,

는 상기 회절격자의 특징 간의 거리이고,

는 상기 광의 상기 회절격자로의 입사각이며,

은 상기 회절격자 측의 재료(예를 들어, 액정)의 굴절률로서 그 재료로부터 광이 상기 회절격자(즉, ‘광-입사' 측)로 입사한다. 수학식 1은 상기 광-입사 측과 반대쪽 상기 회절격자 측의 굴절률이 1의 굴절률을 갖는다고 가정한다. 상기 광-입사 측과 반대측에서 상기 굴절률이 1이 아니면, 수학식 1은 그에 따라 수정될 수 있다. here,

Is the wavelength of the light,

Is a diffraction order,

Is the distance between the features of the diffraction grating,

Is an incident angle of the light to the diffraction grating,

Is a refractive index of a material (for example, liquid crystal) on the side of the diffraction grating, and light is incident on the diffraction grating (i.e., the 'light-incident side') from the material. Equation (1) assumes that the refractive index of the diffraction grating side opposite to the light-incident side has a refractive index of 1. If the refractive index is not 1 at the side opposite to the light-incident side, Equation (1) can be modified accordingly.

Also here, the 'light guide' is defined as a structure and guides the light in the structure using total reflection. In particular, the light guide may comprise a substantially transparent core at the operating wavelength of the light guide. In some instances, the term 'light guide' generally refers to a dielectric optical waveguide that provides total internal reflection to guide light at the interface between the dielectric material of the light guide and the material or medium surrounding the light guide Quot; By definition, the condition for total reflection is that the index of refraction of the light guide is greater than the index of refraction of the surrounding medium directly adjacent to the surface of the light guide material. In some examples, the light guide may include a coating in addition to or in lieu of the refractive index difference described above to provide or facilitate total reflection. In some instances, the coating may be a reflective coating. According to various examples, the light guide may be any of a number of light guides including, but not limited to, one or both of a plate or a slab guide and a strip guide.

Also here, the term 'plate' when applied to a light guide as in a 'plate light guide' is defined to mean a separate or separate planar layer or sheet. In particular, the plate light guide is defined as a light guide configured to guide light in two substantially orthogonal directions bounded by the upper and lower surfaces of the light guide. Further, by definition herein, both the top and bottom surfaces are separated from each other and, in a sense, substantially parallel to each other. That is, within some other small area of the plate light guide, the top and bottom surfaces are substantially parallel or coplanar. In some instances, the plate light guide is substantially planar (e.g., limited to a plane) so that the plate light guide may be a planar light guide. In another example, the plate light guide may be bent in one or two orthogonal dimensions. For example, the plate light guide may be bent in a single dimension to form a cylindrical plate light guide. However, in various examples, the plate light guide has a curvature radius that is sufficiently large to ensure that any curvature is maintained within the plate light guide that guides the light.

) 및 '이상' 굴절률(

) 둘 다를 나타낼 수 있다. 액정에서, 상기 정상 굴절률(

)과 상기 이상 굴절률(

)간의 선택은 상기 액정의 상태를 선택함으로써 제공될 수 있다. 특히, 상기 액정 분자의 배향에 따라서, 특정 편광을 갖는 광은 상기 액정의 상태에 따라 서로 다른 굴절률(예를 들어,

또는

)를 경험할 수 있다. 또한, 다양한 예에 따라, 상기 액정의 상태 및 더 나아가 상기 액정의 굴절률은 전환되거나 변경되어(예를 들어, 열, 전기장 등을 인가하여) 선택적으로 상기 굴절률을 변경할 수 있다. Liquid crystal " or " liquid crystal material " is defined herein as a fluid or liquid having the properties of a crystal. In particular, according to various examples herein, the liquid crystal may exhibit one or more of a nematic phase, a stymatic phase, a chiral phase, or a discotic phase. Further, the liquid crystal or liquid crystal material may exhibit birefringence. Birefringence is a property of a material in which light having different polarizations can experience different refractive indices as the light passes through or interacts with the material. For example, a birefringent crystal such as a birefringent liquid crystal has a so-called " normal " refractive index

) And an 'ideal' refractive index (

). ≪ / RTI > In the liquid crystal, the normal refractive index (

) And the extraordinary refractive index (

) May be provided by selecting the state of the liquid crystal. In particular, depending on the orientation of the liquid crystal molecules, light having a specific polarization may have different refractive indices (for example,

or

). Further, according to various examples, the state of the liquid crystal and further the refractive index of the liquid crystal can be changed or changed (for example, by applying heat, an electric field, etc.) to selectively change the refractive index.

Here, the 'state' of the liquid crystal is an orientation of the predetermined liquid crystal molecules. For example, in a nematic liquid crystal, a rod-shaped molecule (i.e., a nematic liquid crystal) is characterized by a so-called " director " that points in a direction parallel to the long axis of the rod-shaped molecule. The state of the nematic liquid crystal can be switched between (a) alignment of the director substantially parallel to the substrate and (b) alignment of the director substantially perpendicular to the substrate (e.g., by applying an electric field) . By definition, the substantially parallel orientation is referred to as a 'horizontal orientation' and the substantially perpendicular orientation is referred to as a 'vertical orientation'. For example, light having TE (transverse electric) polarization experiences different refractive indices depending on whether the liquid crystal is set to a state corresponding to the horizontal orientation or another state corresponding to the vertical orientation, for example. As such, the state of the liquid crystal can be used to selectively control the refractive index experienced by the light passing through or interacting with the liquid crystal. In addition, the liquid crystal may have one or more " refractive index " states based on different refractive indices that may be produced by different states of the liquid crystal for a given polarization.

Still further, as used herein, "one" is intended to have the ordinary meaning in the patent field, "one or more." For example, 'one grid' means one or more grids, and 'grid' here means 'the plurality of grids' in the present specification. Any reference in this specification to "top", "bottom", "top", "bottom", "top", "down", "front", "rear", "left" ≪ / RTI > As used herein, the term " approximately " when applied to a value generally means that it is within the tolerance range of the equipment used to generate the value, or, in some instances, plus or minus Minus 10%, or plus or minus 5%, or plus or minus 1%. Also, as used herein, the term " about " means, for example, a majority, or most, or all, or an amount in the range of about 51% to about 100%. Furthermore, the embodiments herein are intended to be illustrative only and not for purposes of discussion.

According to some examples of the principles described herein, a liquid crystal coupled light modulator is provided. 1 is a cross-sectional view of a liquid crystal coupled optical modulator 100 according to an example consistent with the principle described herein. 2 is a cross-sectional view of a liquid crystal coupled optical modulator 100 according to another example consistent with the principle described herein. The liquid crystal coupled optical modulator 100 is configured to couples and modulate a part of light propagated as light 102 guided into the liquid crystal coupled optical modulator 100. Both the coupling-out and the modulation are provided for modulating the coupling between the light guide and the diffraction grating using a liquid crystal (LC). According to various examples, the diffraction grating is configured to provide diffractive redirection of a coupled portion of the light 102 from the optical modulator.

In particular, the light from the light source 104 propagates as the light 102 guided by the liquid crystal coupled optical modulator 100. The general propagation direction (i.e., before coupling out) of the guided light 102 in the liquid crystal coupled optical modulator 100 is shown in bold arrows in FIGS. 1 and 2. The liquid crystal coupled optical modulator 100 couples out the guided light 102 and emits the modulated portion as modulated light 106 (shown by dashed arrows in FIGS. 1 and 2). For example, the modulated light 106 may be emitted as a beam of light. In various examples, the beam of modulated light 106 may have a relatively narrow spread angle with a predetermined direction. The modulated light 106 is configured to propagate in a direction away from the liquid crystal coupled optical modulator 100. The propagation direction of the modulated light 106 is substantially different from the propagation direction of the guided light 102 in the liquid crystal coupled optical modulator 100. For example, as a light beam, the modulated light 106 propagates in a direction substantially perpendicular to the general propagation direction of the guided light 102 propagating within the liquid crystal coupled optical modulator 100.

The modulated light 106 (e.g., a modulated light beam) is a function of the state of the liquid crystal that is determined by the coupling out of light or used to modulate the coupling out, such as intensity or brightness, Optical coupling '. In some examples, the liquid crystal (LC) modulated optical coupling is configured to toggle the intensity of the modulated light 106 between two states. The first state or the ON state of the two states may be a full or maximum intensity of the modulated light 106 and a second state or an OFF state may be a state (I. E., Substantially light-free) of the modulated light 106 produced by the combined optical modulator 100. [ In another example, the liquid crystal (LC) modulated optical coupling may produce modulated light 106 having a plurality of intensity values or states. Collectively, the plurality of intensity states may vary between the ON state and the OFF state.

In various examples, the light source 104 may be substantially any light source, including, but not limited to, one or more light emitting diodes (LEDs), fluorescence, and lasers. In some instances, the light source 104 may produce substantially monochromatic guided light 102 having a narrowband spectrum represented by a particular color. In particular, the color of the monochromatic guided light 102 may be a primary color of a particular color range or a color model (e.g., a red-green-blue (RGB) color model). The light source 104 may be a red LED and the monochromatic guided light 102 is substantially red. The light source 104 may be a green LED and the monochromatic guided light 102 is substantially green. The light source 104 may be a blue LED and the monochromatic guided light 102 is substantially blue. In another example, the guided light 102 supplied by the light source 104 has a substantially broadband spectrum. For example, the guided light 102 produced by the light source 104 may be white light. The light source 104 may be fluorescent to generate white light.

As shown in FIGS. 1 and 2, the liquid crystal coupled optical modulator 100 includes a light guide 110. For example, the light guide 110 may include a slab or plate light guide. The light guide (110) is configured to guide the light from the light source (104). In particular, according to various examples, the light guide 110 utilizes total internal reflection to guide the light as guided light 102.

The light guide 110 may include a dielectric configured as an optical waveguide. The dielectric may have a refractive index greater than the refractive index of the medium surrounding the dielectric optical waveguide. Depending on the one or more guided modes, the difference between the refractive index of the dielectric and the surrounding medium in the light guide 110 is configured to facilitate total reflection of the guided light 102. In some examples, the guided light 102 may be coupled to the end of the light guide 110 and propagate along the length of the end. For example, a lens (not shown) may facilitate coupling of light from the end to the light guide 110.

In some instances (e.g., as shown in cross section in Figure 1), the light guide 110 is a slab or plate optical waveguide. According to some examples, the slab or plate optical waveguide may be a sheet of substantially rigid optically transparent material. In some examples, the light guide 110 may include a cladding layer over a portion of the surface (not shown) of the light guide 110. The cladding layer may be used to facilitate total reflection. In some examples, the sheet of optically transparent material of the light guide 110 is a substantially planar sheet of which the dielectric extends. According to various examples, the optically transparent material can be made from various types of glass (e.g., quartz glass, alkali-aluminosilicate glass, borosilicate glass, etc.) and optically clear plastic or polymer (e.g., Acrylate, acrylate, acrylate, acrylate, acrylate), polycarbonate, and the like).

보다 큰 입사각

로 상기 경계면를 접하고 상기 둘러싸는 매체(즉, 상기 경계면에서 상기 광 가이드(110) 외부의 상기 매체)가 상기 광 가이드 굴절률(즉, 전반사 조건)보다 작은 굴절률을 갖는 경우에 발생한다. 여기에서, 상기 임계각

는

로 주어진 수직 경계면에 대해 상대적으로 측정된 각도로서 정의된다. 여기서,

은 상기 광 가이드 굴절률이고

는 상기 광 가이드(110) 외부에서 상기 둘러싸는 매체의 굴절률이다. 다양한 예에 따라서, 상기 전반사는 상기 가이드된 광(102)이 상기 광 가이드(110)에서 가이드되도록 한다. The guided light 102 from the light source 104 may propagate primarily horizontally along the light guide 110, as shown by the solid line arrows in Figures 1 and 2. As described above, the propagation of the guided light 102 in the generally horizontal propagation direction depends on one or more light beams that represent the plane wave of the propagating light associated with the optical mode of one or more of the light guides 110 . In particular, the light beam of the guided light 102 is incident on the light guide 110 due to the difference in refractive index between the material of the light guide 110 and the surrounding medium at the interface between the dielectric of the light guide 110 and the surrounding medium. Can be substantially scattered or reflected at the 'wall' of the light guide 110. Wherein the total reflection is such that the light beam has a critical angle

Greater incident angle

(I.e., the medium outside the light guide 110 at the interface) has a refractive index smaller than the refractive index of the light guide (i.e., the total reflection condition). Here, the critical angle

The

Lt; / RTI > is defined as the relative measured angle relative to a given vertical interface. here,

Is the refractive index of the light guide

Is the refractive index of the surrounding medium outside the light guide (110). According to various examples, the total internal reflection allows the guided light 102 to be guided in the light guide 110.

The liquid crystal coupled optical modulator 100 shown in FIGS. 1 and 2 further includes a diffraction grating 120. Figures 1 and 2 illustrate a plurality of diffraction gratings 120 by way of example. As shown in FIGS. 1 and 2, the diffraction grating 120 is adjacent to or separated from the surface of the light guide 110. As will be described below, the diffraction grating 120 is configured to diffractively redirect a portion of the guided light 102 coupled out through the surface of the light guide 110. According to various examples, the diffraction grating 120 diffracts a coupled-out portion of the guided light 102 from the light guide 110 in a direction different from the direction of propagation of the guided light 102 Redirect. A portion of the guided light 102 that is redirected and couples to diffraction may be directed away from the surface of the light guide 110 at a diffraction angle relative to the surface. For example, the diffraction angle may be between 60 and 120 degrees. As shown in Figs. 1 and 2, the diffraction angle is, for example, about 90 degrees. Coupled out portion of the guided light 102 is the modulated light 106 emitted from the liquid crystal coupled optical modulator 100. The dashed arrows are used to illustrate the modulated light 106 in Figures 1 and 2 to further emphasize the modulation of light.

The diffraction grating 120 may include a plurality of grooves or ridges that each penetrate into or extend from the surface of the material layer. The grooves can be machined or molded on the surface of the material layer. For example, Figure 1 shows the diffraction grating 120 as a plurality of parallel grooves adjacent the light guide 110 but through the top surface of the material layer 122 spaced from the light guide 110. According to some examples, the material layer 122 may be the lid 144 of the hole 140 described below. In another example (not shown), the diffraction grating 120 may be formed on the bottom surface of the material layer 122. For example, the material layer 122 may be a dielectric layer since it includes a dielectric. Also, according to various examples, the material layer 122 may be substantially transparent at the operating wavelength of the liquid crystal coupled optical modulator 100.

In another example (not shown), the diffraction grating 120 may be a film or layer applied or adhered to the surface of the material layer 122. According to various examples, the film may include bumps, grooves, etc. to form the diffraction grating 120. For example, the film or layer providing the diffraction grating 120 may be applied to the top surface of the material layer 122. In another example (not shown), the film or layer providing the diffraction grating 120 may be applied to the bottom surface of the material layer 122.

In another example, the diffraction grating 120 may comprise a material modification within the material layer 122 itself. For example, the material layer 122 may have a refractive index that varies in a direction substantially parallel to the surface of the material layer 122 to produce diffraction. In another example, the diffraction grating 120 may be a layer including, but not limited to, a patterned metal layer (e.g., a thin and long piece of metal) to provide diffraction. The patterned metal layer may be used, for example, as a reflective diffraction grating 120.

In some instances, the diffraction grating 120 is diffracted as the diffraction grating 120 and passes through or substantially through the diffraction grating 120. In another example, the diffraction grating 120 is incident on the diffraction grating 120 as a diffraction grating 120, and is diffractingly redirected and reflected by the diffraction grating 120. In some examples, the groove, ridge or other feature defining the diffraction grating 120 is substantially perpendicular to the propagation direction of the guided light 102 in the light guide 110. In another example, the grooves, ridges, or other features may be oriented on the surface at an angle (e.g., at an angle other than perpendicular) in the propagation direction.

The liquid crystal coupled optical modulator 100 further includes a liquid crystal 130 interposed between the diffraction grating 120 and the light guide 110. For example, as shown in FIGS. 1 and 2, the liquid crystal 130 is interposed between the material layer 122 including the diffraction grating 120 and the upper surface of the light guide 110 .

In various examples, the liquid crystal 130 is in contact with the surface of the light guide 110. In some examples, the liquid crystal 130 may contact only a portion of the light guide surface. For example, as shown in FIG. 1, the liquid crystal 130 contacts only a portion of the light guide surface corresponding to the vicinity of the diffraction grating 120. 2 illustrates that the liquid crystal 130 is substantially in contact with the entire upper surface of the light guide 110. FIG.

The liquid crystal 130 has a first refractive index state (i.e., a first refractive index state) configured to prevent total reflection at the surface of the light guide 110. In some examples, the first index of refraction is configured to substantially match or exceed the index of refraction of the light guide 110 (or of the material thereof). The first index of refraction prevents total reflection on the surface of the light guide 110 by substantially violating or not supporting the condition for total reflection. In particular, " preventing total reflection " herein means that total reflection is substantially prevented or not substantially occurred at the surface in contact with the liquid crystal 130 having the first refractive index. In particular, since the first refractive index does not support the total reflection condition at the light guide surface, the first refractive index of the liquid crystal 130, which is in contact with the surface of the light guide 110, substantially prevents total reflection at the surface. By preventing total reflection at the surface, a portion of the guided light 102 may escape or leach out of the light guide 110 and enter into the liquid crystal 130.

In addition, the liquid crystal 130 has another state (i.e., a second refractive index state) having a second refractive index configured to facilitate total internal reflection in the light guide 110. Here, 'facilitating total reflection' means that total reflection occurs or occurs at the surface in contact with the liquid crystal 130. In particular, the second refractive index on the surface satisfies or exceeds the total reflection condition of the light guide 110. According to various examples, the second index of refraction is generally smaller than the refractive index of the light guide 110 and is substantially smaller in some instances.

)일 수 있고, 상기 제2 굴절률이 상기 이상 굴절률(

)일 수 있다. 다른 예에서, 상기 제1 굴절률이 상기 이상 굴절률(

)일 수 있고 상기 제2 굴절률이 상기 정상 굴절률(

)일 수 있다. 또 다른 예에서, 상기 액정(130)의 상기 제1 및 제2 굴절률 중 하나 또는 둘 다는 상기 이상 굴절률(

)과 상기 정상 굴절률(

)이 아닐 수 있다. In some examples, the first refractive index is less than the normal refractive index

), And the second refractive index may be the extraordinary refractive index (

). In another example, when the first refractive index is less than the extraordinary refractive index (

) And the second refractive index is the normal refractive index (

). In another example, one or both of the first and second refractive indexes of the liquid crystal 130 may be different from the ideal refractive index

) And the normal refractive index (

).

According to some examples, the index of refraction (the 'optical guide refractive index') of the optical guide material and the refractive index of the first liquid crystal of the liquid crystal, respectively, when the respective refractive indexes have values within about 10 percent to about 20 percent of each other or below The first refractive index of the refractive index state is defined as being 'substantially matched'. In some instances, if the difference between the refractive indices is within about 5 percent, it is considered to be consistent. In some instances, if the difference between the refractive indices is within about 5 percent, it is considered to be a match. By definition herein, for example, a first refractive index of about 1.55 can be considered to match or exceed a refractive index of the optical guide of about 1.5. By definition, when the first refractive index is larger than the refractive index of the light guide, the first refractive index exceeds the refractive index of the light guide. For example, by definition, if the first index of refraction is 1 percent greater than the index of refraction of the light guide, the first index of refraction 'exceeds' the index of refraction of the light guide.

In various embodiments, the second refractive index of the liquid crystal 130 is configured to be sufficiently low relative to the refractive index of the light guide to substantially confine light within the light guide 110 by total internal reflection. In particular, by definition herein, the second index of refraction can be considered to be less than the index of refraction of the light guide 110 if the total reflection condition of the light guide 110 is satisfied. In some examples, the second refractive index is considered sufficiently small or small if the respective refractive index values are different from each other by about 5 percent to about 20 percent and the refractive index of the light guide material is greater than the second refractive index. For example, a second refractive index of about 1.4 would be about 7 percent smaller than the refractive index of the light guide of about 1.5, thereby facilitating total reflection. However, according to some examples, the second index of refraction can be used because it is still less than the index of refraction of the light guide and can still substantially facilitate total internal reflection.

The liquid crystal 130 may be substantially limited to a portion of the light guide surface associated with the diffraction grating 120, as described above. In particular, as shown in FIG. 1, the liquid crystal 130 is substantially limited in contact with the upper surface of the light guide 110 from the outside of the upper surface thereof. Also, the liquid crystal 130 shown in FIG. 1 is positioned below the diffraction grating 120, that is, between the diffraction grating 120 and the light guide 110. For example, the liquid crystal 130 may be confined to or in the vicinity of the diffraction grating 120 by a hole on the surface of the housing or the light guide 110.

In particular, the liquid crystal coupled optical modulator 100 may further include apertures 140 to confine the liquid crystal 130 adjacent its surface at the surface of the light guide 110. The aperture 140 may include a pair of walls 142, 142 'adjacent the light guide surface and extending away from the surface. The hole 140 further includes a lid 144 to further fill the gap between the walls 142 and 142 '. 1, the lid 144 may be the material layer 122 (e.g., a dielectric layer) that supports or includes the diffraction grating 120. The pair of walls 142 and 142 'and the lid 144 are configured to limit the liquid crystal 130 that is in contact with the surface of the light guide 110 together. The lid 144 may be made of an optically transparent dielectric (e.g., glass or plastic). In addition, the lid 144 may include or at least support the diffraction grating 120. In some instances, the walls 142 and 142 'may also be optically transparent dielectrics.

In another example (see FIG. 2), the liquid crystal 130 is located in a layer or space along a portion (e.g., the entire length) of the light guide 110 associated with the plurality of diffraction gratings 120. 2, the liquid crystal 130 may be confined between the light guide 110 and a material layer or sheet 122 that is substantially parallel to the light guide 110. As shown in FIG. For example, the diffraction grating 120 may be located on the material layer or sheet 122.

The liquid crystal 130 may substantially include any liquid crystal material having a first state and a second state with different refractive indices. Here, the refractive index in the first state substantially coincides with or exceeds the refractive index of the optical guide to prevent total reflection. For example, as described above, the liquid crystal 130 may be a nematic liquid crystal (that is, a liquid crystal material showing a nematic phase, a chiral or a cholesteric nematic phase, etc.), a smectic liquid crystal (for example, A liquid crystal material exhibiting phase A or smectic phase C), a discotic liquid crystal, and various other birefringent liquid crystal materials.

In some instances, the liquid crystal 130 may be characterized in that one state (e. G., The first refractive index state) is characterized by a horizontal orientation of the nematic liquid crystal molecules and another state (e. G., The second refractive index state) Comprises a nematic liquid crystal provided by the vertical orientation of the nematic liquid crystal molecules. The horizontal orientation may provide the first index of refraction and the vertical orientation may provide the second index of refraction. Alternatively, in another example, the vertical orientation may provide the first index of refraction and the horizontal orientation may provide the second index of refraction.

For example, transverse electric (TE) polarized light (e.g., light 102) may pass through the nematic liquid crystal 130 in a first refractive index state provided by the horizontal orientation, . The TE polarized light experiences a relatively lower refractive index when facing the same nematic liquid crystal 130 in the second refractive index state due to the vertical alignment. The relatively higher refractive index of the first refractive index state matches or exceeds the refractive index of the light guide 110 and is prevented from total reflection with respect to the TE polarized light. The modulated light 106 is coupled to the outside of the light guide 110 when the nematic liquid crystal 130 is in the first refractive index state and the guided light 102 is TE polarized, 120 to diffractively produce and release (i. E., The modulated light 106) from the liquid crystal coupled optical modulator 100. Alternatively, the refractive index of the nematic liquid crystal 130 in the vertical alignment state experienced by the TE polarized light may be sufficiently lower than the refractive index of the light guide 110 to facilitate total reflection, The emission of the modulated light 106 from the combined optical modulator 100 can be substantially prevented or at least minimized.

In another example, light (e.g., light 102) having transverse magnetic polarization (TM) may experience a relatively lower refractive index when interacting with the nematic liquid crystal 130 in the horizontally oriented state , It is possible to experience a relatively higher refractive index when encountering the same nematic liquid crystal 130 having the vertical orientation. Still further, if the relatively higher refractive index (second refractive index state) substantially matches or exceeds the refractive index of the light guide material, total internal reflection can be prevented. Thus, total reflection with the nematic liquid crystal 130 in the vertically aligned state with respect to the TM polarized light can be prevented. This total reflection means that the guided light 102 is coupled out of the light guide 110 and diffractive redirecting of the coupled out light by the diffraction grating 120 can be facilitated. It will be appreciated that many other permutations of refractive index (i. E., The first and second refractive index states), optical polarization, and refractive index of the light guide are possible. All such permutations are within the scope of the principles described herein.

Examples of the liquid crystal material usable as the liquid crystal 130 include 4'-pentyl-4-biphenylcarbonitrile, 4-trans-pentylcyclohexylbenzonitrile, MLC-9200-00, MLC-9200-100, MLC 6241-000, MLC-6608, TL-216 and E44. For example, 4'-pentyl-4-biphenylcarbonitrile exhibits a refractive index of about 1.5 for TE polarized light and a refractive index of about 1.7 for TM polarized light in the vertically aligned state. However, in the horizontally oriented state, 4'-pentyl-4-biphenylcarbonitrile exhibits a refractive index of about 1.7 for TE polarized light and a refractive index of about 1.5 for TM polarized light. 4'-Pentyl-4-biphenylcarbonitrile is commercially available as 5CB liquid crystal from Sigma-Aldrich, LLC, St. Louis, Mo., USA. 4-trans-pentylcyclohexylbenzonitrile is commercially available as 5PCH liquid crystals manufactured by Maison Chemical Co Ltd, China. The liquid crystals MLC-9200-00, MLC-9200-100, MLC-6241-000, MLC-6608, TL-216 and E44 are manufactured by Merck of Darmstadt, Germany.

In some examples, the liquid crystal coupled light modulator 100 further includes an electrode 150. The electrode 150 is used to provide an electric field that produces one or both of the first refractive index state and the second refractive index state of the liquid crystal 130. For example, the electric field may generate the first refractive index state of the liquid crystal 130 and cause the liquid crystal 130 to return to the second refractive index state in the absence of the electric field. In another example, the second refractive index state can be generated by applying the electric field, and the first refractive index state is provided in the absence of the electric field. In another example, a first electric field provided by the electrode 150 produces the first refractive index state and a second electric field provided by the electrode 150 generates a second refractive index state of the liquid crystal 130 .

In some examples, a plurality of electrodes 150 may be used to create the electric field across the liquid crystal 130. [ In particular, the liquid crystal coupled optical modulator 100 includes a first electrode 150 and a second electrode 150 'located on both sides of the liquid crystal 130, An electric field can be provided. In Figure 1, by way of non-limiting example, the second electrode 150 'is shown on the lid 144 of the hole 140, and the first electrode 150 is shown on the top of the light guide 110 Is shown on the rear surface. In another example (not shown), the first electrode 150 may be located on the back or bottom of the hole 140 (e.g., the light guide surface) instead of the back surface of the light guide 110 have. In another example, as shown in FIG. 2, the electrodes 150 and 150 'are disposed on the opposite surface of the liquid crystal 130 and below (e.g., the lower surface of the diffraction grating 120, (The upper surface of the substrate 110). In some examples, for example, as shown in FIG. 2, the pair of first and second electrodes 150, 150 'may be aligned with the corresponding diffraction grating 120 of the plurality of diffraction gratings 120 have. According to various examples, one or both of the first electrode 150 and the second electrode 150 'may be formed of indium tin oxide (ITO), fluorine doped tin oxide (FTO), doped zinc oxide, or various conductive organic films , ≪ / RTI > and the like.

The electric field provided by applying a first voltage to the electrodes 150, 150 'may be used to change one or both of the states and set the first refractive index state of the liquid crystal 130 in contact with the light guide 110 . The application of the second voltage to the electrodes 150 and 150 'may be used to change one or both of the states and to set the first refractive index state of the liquid crystal 130 in contact with the light guide 110 . In some examples, one of the first and second voltages is approximately 0 V and the other voltage is substantially different from 0 V to cause the change or to set the condition. In some examples, one or both of the first and second voltages represent an alternating current (AC) voltage. According to various examples, the pair of first and second electrodes 150, 150 'may be selectively activated to turn on or turn off the corresponding diffraction grating 120 along the light guide 110 .

In some instances, the liquid crystal coupled light modulator 100 is substantially transparent. Particularly, according to some examples, the light guide 110, the diffraction grating 120, and the liquid crystal 130 at least in the first refractive index state are arranged in a direction orthogonal to the direction of the light propagation in the light guide 110 And can be optically transparent. For example, optical transparency may cause an object on one side of the liquid crystal coupled optical modulator 100 to be visible on the opposite side.

)과 일치하거나 초과하는 상기 제1 굴절률(

)을 갖는 상기 제1 굴절률 상태(즉,

)에 있는 상기 액정(130)을 갖는 상기 액정 결합 광변조기(100)를 도시한다. 도 3b은 상기 액정(130)이 상기 광 가이드 굴절률(

)보다 작은 상기 제2 굴절률(

)을 갖는 상기 제2 굴절률 상태(즉,

)에 있음을 도시한다. 또한, 도 3a 및 도 3b는 실질적으로 상기 광 가이드 표면의 외부에 제한되어 있으나 그 표면에 접촉하는 상기 액정(130)을 도시한다. 3A is a cross-sectional view of a portion of a liquid crystal coupled optical modulator 100 in accordance with an example consistent with the principles described herein. FIG. 3B is a cross-sectional view of a portion of the liquid crystal coupled optical modulator 100 of FIG. 3A in accordance with an example consistent with the principles described herein. In particular, FIG. 3A illustrates the relationship between the refractive index of the material of the light guide 110

) Or greater than the first refractive index

The first refractive index state (i.e.,

The liquid crystal coupled optical modulator 100 having the liquid crystal 130 in the liquid crystal cell 100 is shown. 3B illustrates a state in which the liquid crystal 130 has a refractive index

) Smaller than the second refractive index (

The second refractive index state (i.e.,

). ≪ / RTI > 3A and 3B illustrate the liquid crystal 130 that is substantially restricted to the outside of the light guide surface but contacts its surface.

3A, a relative value of the refractive indexes of the liquid crystal 130 and the light guide 110 prevents the total reflection, and the guided light 102 couples out from the light guide 110 And is coupled to the diffraction grating 120. The coupled-out light 102 'is shown by hollow arrows in FIG. 3A. For example, the refractive index of the light guide material may be about 1.7, and the first refractive index state of the liquid crystal 130 may have a vertical orientation (i.e., guided light 102) of the liquid crystal molecules causing a refractive index of about 1.7, For example). The agreement between the refractive indexes in 1.7 prevents the surface of the light guide 110 from being substantially separated from the liquid crystal 130 and thereby prevents total reflection of the light 102 guided by the light guide 110 .

3B, the liquid crystal 130 has been converted to the second refractive index state provided by the horizontal orientation of the molecules of the liquid crystal 130 having a refractive index of about 1.5 (i.e., for the guided light 102) . 3B, when the refractive index of the liquid crystal 130 is smaller than the refractive index of the light guide 110, the total reflection is facilitated. Thus, as shown in FIG. 3B, the guided light 102 is not coupled to the outside of the light guide 110.

In some instances, the first refractive index state may be provided only in the vicinity of the diffraction grating 120 (e.g., by applying an electric field), as shown by a darker shaded area in FIG. To facilitate guiding of light 102 guided along the light guide 110 by total internal reflection outside the vicinity of the diffraction grating, the liquid crystal may be maintained in the second refractive index state have.

According to some examples of the principles described herein, an electronic display is provided. FIG. 4 shows a block diagram of an electronic display 200 according to an example consistent with the principles described herein. The electronic display 200 modulates the pixels of the display 200 using liquid crystal coupling modulation. Also, the emitted modulated light 206 may preferentially be directed in the field of view of the electronic display 200.

The electronic display 200 shown in FIG. 4 includes a light guide 210. The light guide 210 is configured to direct light 202 from a light source 212. For example, the light guide 210 may be a backlight light guide of the electronic display 200. According to some examples, the light 202 from the light source 212 is guided between the front and back surfaces of the light guide 210 by total internal reflection. For example, the light source 212 may be substantially similar to the light source 104 described above with respect to the liquid crystal coupled optical modulator 100. Further, in some examples, the light guide 210 may be substantially similar to the light guide 110 described above with respect to the liquid crystal coupled optical modulator 100. For example, the light guide 210 may be a slab or a plate optical waveguide.

As shown in FIG. 4, the electronic display 200 further includes a plurality of diffraction gratings 220 adjacent to but spaced from the surface of the light guide 210. The plurality of diffraction gratings 220 are configured to diffractively redirect a portion of the guided light 202 couples out through the surface of the light guide 210. In particular, the plurality of diffraction gratings 220 may diffractively redirect different coupled-out portions 202 'of the guided light 202, respectively. According to some examples, the plurality of diffraction gratings 220 are substantially similar to the diffraction gratings 120 described above for the liquid crystal combined light modulator 100. For example, the plurality of diffraction gratings 220 may include a plurality of features (e.g., grooves, ridges, bumps, holes, or holes) in a layer adjacent to, but spaced from, Or combinations thereof). In some examples, the different plurality of diffraction gratings 220 are selectively configured to diffractively redirect the different coupled-out portions 202 'of the guided light 202, and additionally, (3D) electronic display 200 can be constructed by redirecting the portions 202 'diffractably in different directions.

The electronic display 200 further includes a liquid crystal 230 contacting the light guide 210 and the diffraction grating 220. The liquid crystal 230 has a selectable first refractive index state having a first refractive index in order to prevent total reflection in the light guide 210. The liquid crystal 230 has a selectable second refractive index state having a second refractive index to facilitate the total reflection. In particular, the first index of refraction is substantially equal to or greater than the index of refraction of the light guide 210, and the second index of refraction is less than the index of refraction of the light guide 210. The selection of the diffractive grating 220 corresponding to the selectable first and second refractive index states is configured to modulate the portion 202 'of the coupled out light as the modulated pixel of the electronic display 200. Specifically, the pixel of the electronic display 200 includes the portion 206 of the guided light modulated by the selection between the first and second refractive index states, which is couched out and diffractively redirected.

In some examples, the liquid crystal 230 is substantially similar to the liquid crystal 130 described above with respect to the liquid crystal coupled optical modulator 100. In particular, the first refractive index state may comprise an orientation of the liquid crystal molecules 230 configured to provide the first refractive index. Similarly, the second refractive index state may comprise another orientation of the liquid crystal molecules configured to provide the second refractive index. The first index of refraction may be configured to substantially match or exceed the index of refraction of the light guide 210 with respect to a predetermined polarization of the guided light. The second refractive index of the liquid crystal may be configured to be substantially different from the refractive index of the light guide 210 with respect to a predetermined polarization of the guided light. The selective or controlled state of the liquid crystal molecules in the vicinity of the plurality of corresponding diffraction gratings 220 is determined by the modulation of the light emitted by the electronic display 200 (e.g., the pixel is turned on and turned off Lt; / RTI > For example, an electrode (not shown) may be provided to selectively control the diffractive coupling from each of the plurality of diffraction gratings 220 to modulate the individual pixels.

According to some examples of the principles described herein, a liquid crystal coupled light modulation method is provided. Particularly, in the liquid crystal combined light modulation method, liquid crystal is used to modulate light by preventing and facilitating total internal reflection alternately in a light guide. The liquid crystal exhibits a refractive index that substantially coincides with or exceeds the refractive index of the light guide, thereby preventing total reflection. The liquid crystal exhibits a different refractive index than the refractive index of the light guide material, thereby facilitating total reflection. According to some examples, the liquid crystal combined light modulator may be the liquid crystal combined light modulator 100 described above.

5 is a flow diagram of a liquid crystal coupled light modulation method 300 according to an example consistent with the principles described herein. The liquid crystal coupled light modulation method 300 includes a step 310 of guiding light in a light guide using total internal reflection (TIR). In some examples, the light guide may be substantially similar to the light guide 110 described above with respect to the liquid crystal coupled light modulator 100. In particular, in some examples, the light guide comprises a rigid sheet or slab of substantially rigid material optically transparent to guide (310) the light in the sheet by total internal reflection. The step 310 of guiding light through the light guide may include light propagating in the slab between the top and bottom surfaces of the sheet.

The liquid crystal coupled light modulation method 300 further includes a step 320 of switching the state of the liquid crystal between a first state (i.e., a first refractive index state) and a second state (i.e., a second refractive index state). The liquid crystal is in contact with the surface of the light guide and further interposed between the light guide surface and the diffraction grating. According to some examples, the refractive index of the liquid crystal in the first refractive index state substantially coincides with or exceeds the refractive index of the light guide to prevent total reflection, and in the second refractive index state, the liquid crystal refractive index is smaller than the refractive index of the optical guide . In some examples, the liquid crystal may be substantially similar to the liquid crystal 130 described above with respect to the liquid crystal coupled optical modulator 100. Further, in some examples, as described above, the diffraction grating may be substantially similar to the diffraction grating 120 described above for the liquid crystal combined light modulator 100. [

In some instances, step 320 of switching the state of the liquid crystal may include applying one or both of applying the electric field to the liquid crystal and changing the electric field applied to the liquid crystal. For example, the electric field can be applied by using electrodes such as, but not limited to, the electrode 150 or the electrode pair 150, 150 'described above for the liquid crystal coupled optical modulator 100 .

The liquid crystal coupled light modulation method 300 further includes coupling (330) a portion of the guided light externally by preventing total reflection. In particular, when the liquid crystal in contact with the surface is converted (320) to the first refractive index state, a portion of the guided light couples out through the light guide surface. However, according to various examples, when the liquid crystal is converted (320) to the second refractive index state, substantially no total reflection guided light is coupled out. In particular, in the second state, the liquid crystal facilitates total internal reflection and substantially prevents the guided light from escaping the light guide.

에 따를 수 있다. In some examples, the liquid crystal coupled light modulation method 300 further comprises transmitting (340) the coupled-out portion of the guided light to the diffraction grating. For example, the transmitting step 340 may include propagating a portion of the coupled-out guide light through the liquid crystal. In some examples, the liquid crystal coupled light modulation method 300 further includes redirecting (350) the transmitted coupled-out portion of the guided light to the diffraction grating by diffractive redirection. For example, the diffractive redirection may be defined by the diffraction angle < RTI ID = 0.0 >

.

Therefore, an example of a liquid crystal coupled light modulation method for alternately facilitating and preventing total reflection of a light guide using a liquid crystal to modulate light coupled to a liquid crystal coupled optical modulator, an electronic display, and the light guide is described. It is to be understood that the above-described embodiments are merely illustrative of some of the many specific embodiments that represent the principles described herein. Obviously, one skilled in the art can readily devise many different forms without departing from the scope defined by the following claims.

Claims (15)

As a liquid crystal coupling light modulator,
A light guide for guiding light by total internal reflection (TIR);
Diffraction grating; And
A liquid crystal interposed between the diffraction grating and the light guide, the liquid crystal having a first refractive index for preventing total reflection at the surface of the light guide and another state having a second refractive index for facilitating total reflection,
/ RTI >
In a first refractive index state, the liquid crystal couple out a portion of the guided light to the diffraction grating, and the diffraction grating provides some diffractive redirection couples out of the optical modulator.
Liquid crystal coupled light modulator. The method according to claim 1,
Wherein the light guide is a plate light guide comprising a sheet of optically transparent material. The method according to claim 1,
Wherein the diffraction grating is a transmissive diffraction grating. The method according to claim 1,
Wherein the first refractive index substantially coincides with or exceeds the refractive index of the light guide, and the second refractive index is smaller than the refractive index of the light guide. The method according to claim 1,
And the liquid crystal is substantially restricted to a part of the surface of the light guide. The method according to claim 1,
Wherein the liquid crystal comprises a nematic liquid crystal wherein a first refractive index state is characterized by a horizontal orientation of molecules of the nematic liquid crystal and a second refractive index state is characterized by a vertical orientation of molecules of the nematic liquid crystal, Wherein the orientation provides the first index of refraction and the vertical orientation provides the second index of refraction. The method according to claim 1,
Further comprising a first electrode and a second electrode for applying an electric field to the liquid crystal,
Wherein the application of the electric field is adapted to switch the liquid crystal between the first refractive index state and the second refractive index state. As an electronic display,
A liquid crystal display device comprising the liquid crystal coupling light modulator of claim 1,
Wherein a portion of the liquid crystal that is redirected to the diffracting properties of the coupled light guided according to the control of the first and second refractive index states is a modulated light of a pixel of the electronic display,
Electronic display. As an electronic display,
A light guide for guiding light from the light source by total reflection;
A plurality of diffraction gratings; And
A liquid crystal interposed between the diffraction grating and the light guide, the liquid crystal being interposed between the diffraction grating and the light guide, wherein the liquid crystal has a first refractive index for preventing total reflection, Having different states with a second refractive index,
/ RTI >
In the first refractive index state, the liquid crystal couples a part of the guided light and transmits it to the plurality of diffraction gratings so as to be diffracted redirected,
Wherein the pixel of the electronic display comprises a portion of guided light that is selectively modulated between first and second refractive index states, coupled out and diffractively redirected,
Electronic display. 10. The method of claim 9,
Wherein the first refractive index state comprises an orientation of the liquid crystal molecules to provide the first refractive index and the second refractive index state comprises another orientation of the liquid crystal molecules to provide the second refractive index, Wherein the first refractive index substantially coincides with or exceeds the refractive index of the light guide for a predetermined polarization of light and the second refractive index of the liquid crystal is smaller than the refractive index of the light guide for a predetermined polarization of the guided light. 10. The method of claim 9,
Wherein the light guide is a backlight comprising a slab of optically transparent material having a front surface and a back surface,
Wherein the liquid crystal is confined to a portion of the front surface of the light guide, and wherein the diffraction grating comprises a transmissive diffraction grating. 10. The method of claim 9,
Wherein different diffraction gratings of the plurality of diffraction gratings couples out a portion of the guided light in different directions to produce a three-dimensional (3D) electronic display. 10. The method of claim 9,
Further comprising a first electrode and a second electrode,
Wherein application of a first voltage across the first and second electrodes is for generating a first refractive index state of the liquid crystal and application of a second voltage to the first and second electrodes is applied to a second refractive index state of the liquid crystal To produce a display. As a liquid crystal coupling light modulation method,
Guiding light in a light guide using total internal reflection (TIR);
Converting the liquid crystal between a first state and a second state, the liquid crystal being in contact with and interposed between the surface of the light guide and the diffraction grating; And
Coupling-out a part of the guided light by preventing total reflection when the liquid crystal is switched to the first state
Lt; / RTI >
The refractive index of the first state substantially coincides with or exceeds the refractive index of the optical guide to prevent total internal reflection, and in the second state, the refractive index is smaller than the refractive index of the optical guide,
Liquid crystal coupled light modulation method. 15. The method of claim 14,
Transmitting a coupled-out portion of the guided light to the diffraction grating; And
And redirecting the transmitted coupled-out portion of the guided light by diffractive redirection in the diffraction grating.

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